She’s totally buying it 這是一句美國俚語，在這里buy=believe，是相信的意思。

例句：

He said he could help me get a job at his company but I don’t buy it. He doesn’t have that much influence.

他說他能在他的公司幫我找到一份工作，我才不相信呢。他在公司沒什么影響力的。

She told me she loved me but I don’t buy it. I saw her at dinner with her ex-boyfriend last night.

她說她愛我，但我不信，那天晚上我還看見她和她的前男友在一起吃飯。